Method and system for bi-directional communication over a single optical fiber

ABSTRACT

Gigabit Ethernet connectivity is realized using off-the-shelf GIGABIT INTERFACE CONVERTER transceivers, wave division multiplexer/demultiplexers, and a single optical fiber. Simultaneous and bi-directional optical communication over a single optical fiber connecting two or more nodes is achieved by using at least one GIGABIT INTERFACE CONVERTER transceiver having at least one optical signal output and an optical signal input that are of different wavelengths from each other.

FIELD OF THE INVENTION

The present invention relates to a system and method for providingoptical Ethernet connectivity. Particularly, the present invention isconcerned with providing Gigabit Ethernet connectivity using WaveDivision Mulitplex communication over a single optical fiber.

BACKGROUND OF THE INVENTION

In recent years, local area network (LAN) applications have become moreand more prevalent as a means for providing communications betweenpersonal computers, work stations and servers. Because of the breadth ofits installed base, the 1 OBASE-T implementation of Ethernet remains themost pervasive, if not the dominant, network technology for LANs.However, as the need to exchange information becomes more and moreimperative, and as the scope and file size of the information beingexchanged increases, higher and higher communication speeds (i.e.,greater bandwidth) are required from network interconnect technologies.Among the high-speed LAN technologies currently available, fastEthernet, commonly termed 100BASE-T, has emerged as the cleartechnological choice. Fast Ethernet technology provides a smooth,non-disruptive evolution from the 10 megabit per second (Mbps)performance of 10BASE-T applications to the 100 Mbps performance of100BASE-T. The growing use of 100BASE-T interconnections between serversand desktop personal computers is creating a definite need for an evenhigher speed network technology at the backbone and server level.

In an attempt to address the need for faster data communications,various groups have developed standards that specify high speed datatransfers between components of data communication systems. For exampleIEEE standards 802.3ab and 802.3z define Ethernet systems fortransferring data at rates up to one gigabit per second (1 Gbit/s). IEEEstandard 802.3ae defines an Ethernet system for transferring data atrates up to 10 Gbits/s. These standards are now utilized in GigabitEthernet or 1000Base-T interconnections.

With the advent of Gigabit Ethernet or 1000Base-T interconnections,Gigabit Interface Converters (GIGABIT INTERFACE CONVERTER) are becomingincreasingly popular for providing 1000BASE-T connectivity. GIGABITINTERFACE CONVERTERs conform to well-defined specifications and operateby the standards set by the above-mentioned IEEE standards, as well asnon-IEEE standards, such as Gigabit Media Independent Interface (GMII)or Extended Gigabit Media Independent Interface (EGMII). Also, GIGABITINTERFACE CONVERTERs have become readily available as off-the-shelfcomponents that make the design and implementation of a Gigabit Ethernetnetwork or backbone relatively simple and economical.

The GIGABIT INTERFACE CONVERTER specification was developed by a groupof electronics manufactures in order to arrive at a standard small formfactor transceiver module for use with a wide variety of serialtransmission media and connectors. The specification defines theelectronic, electrical, and physical interface of a removable serialtransceiver module designed to operate at Gigabit speeds. A GIGABITINTERFACE CONVERTER provides a small form factor pluggable module whichmay be inserted and removed from a host or switch chassis withoutpowering off the receiving socket. The GIGABIT INTERFACE CONVERTERstandard allows a single standard interface to be changed from a firstserial medium to an alternate serial medium by simply removing a firstGIGABIT INTERFACE CONVERTER module and plugging in a second GIGABITINTERFACE CONVERTER module having the desired alternate media interface.

The GIGABIT INTERFACE CONVERTER standard can provide communications overcopper wire or optical fibers. GIGABIT INTERFACE CONVERTER allowsnetwork managers to configure each gigabit port on a port-by-port basisfor short-wave (SX), long-wave (LX), long-haul (LH), and copper (CX)physical interfaces. LH GIGABIT INTERFACE CONVERTERs extend thesingle-mode fiber distance from the standard 5 km to 10 km. In additionto single-mode fiber, multi-mode fiber is also utilized as a medium foroptical data transmission in a 1000Base-T network.

As schematically illustrated in FIG. 1, in a full-duplex 1000Base-Tconfiguration 1 using GIGABIT INTERFACE CONVERTERs 2 and 3, two separateoptical fibers 4 and 5 are needed to achieve simultaneous datatransmission in two directions between two stations on a point-to-pointlink. A first optical fiber 5 carries optical signals from node A tonode B in a first direction, and a second optical fiber 4 carriesoptical signals from node B to node A in a second direction, opposite tothe first direction. Such a configuration is schematically illustratedin FIG. 1. In another configuration, an optical communication pipe, notshown, is created by bundling a plurality of optical fiber pairs. Aplurality of GIGABIT INTERFACE CONVERTER transceivers can be trunkedtogether with multiple pairs of optical fiber to create a highband-width pipe. Such a configuration may be of an array 2-channel,4-channel, or 8-channel of GIGABIT INTERFACE CONVERTER transceiverstrunked together.

At the present time, a Hewlett Packard™ GIGABIT INTERFACE CONVERTER with1.25 Gbps transmission speed can be purchased for about $126, and a3COM™1000BASE-LX GIGABIT INTERFACE CONVERTER can be purchased for$1,020.00. As for the optical transmission medium, the connection ofvarious nodes in a network are usually owned by communications companiessuch as Sprint™, AT&T™, and the like. Since it is prohibitivelyexpensive to create a fiber optic network infrastructure from the groundup, most companies needing fiber optic connections for their networkfind it most practical to lease fiber optic lines.

Leasing costs are generally based on the number of fibers needed and thedistance through which optical data are to be transmitted. For example,a 15-mile single-fiber connection lease may cost about $1 million for 5years in the United States. As noted above, existing standards andtechnology require that GIGABIT INTERFACE CONVERTER ethernetconnectivity use a minimum of two fibers for full-duplex opticalcommunication. Thus, at least two optical fibers must be leased for aminimum configuration of Gigabit Ethernet using GIGABIT INTERFACECONVERTERs.

When Asynchronous Transfer Mode (ATM) or cell relay communication iscommonly used as the backbone or core of communications networks, it isknown to utilize methods and apparatus for full-duplex bi-directionallong-haul communication using a single optical fiber using Wave DivisionMultiplexing (WDM) and laser-based transceivers.

As an example, U.S. Pat. No. 5,452,124 to Baker discloses a four-portWDM filter and a single erbium-doped optical amplifier to implement adual wavelength bi-directional single fiber optical amplifier module.Baker discusses conventional two-fiber transmission and its drawback,and introduces WDM technology and a single-fiber bi-directionalcommunication system. The focus of Baker is, however, an optical lineamplifier module for the single-fiber bi-directional communicationsystem.

In another example, U.S. Pat. No. 6,211,978 to Wojtunik discloses amultichannel wave division multiplex system for simultaneousbi-direction transmission through a single optical fiber. Wojtunikteaches modulated light signals having the same wavelength traveling inopposite directions over a single fiber at the same time. In yet anotherexample, U.S. Pat. No. 5,6333,741 to Giles discloses multichanneloptical fiber communications having bi-directional transmission with atleast two WDM channels in opposite transmission directions in a singlefiber. More WDM communication systems are disclosed in U.S. Pat. No.5,909,294 to Doerr et al., U.S. Pat. No. 6,130,775 to Yang, U.S.2001/0038478A1 and 2001/0038477A1 to Hwang, and Liaw et al.'s“Multichannel Bidirectional Transmission using a WDM/MUX/DMUX pair andUnidirectional In-Line Amplifiers” IEEE Photonics Technology Letters,Vol. 9, No. 12, December 1997.

These WDM communication systems, although varied in their design, aregenerally found in ATM communication systems, and require anextraordinarily high-cost investment in customized hardware andsoftware. The cost for designing and implementing a WDM communicationsystem, without the optical fiber, can be about a quarter of a millionto several millions of dollars. Accordingly, single fiber bi-directionoptical signal transmission currently is very expensive.

SUMMARY OF THE INVENTION

There is a need for an economical solution to reduce the number ofoptical fibers needed for full-duplex data transmission whilemaintaining the capacity, reliability and cost efficiency of GIGABITINTERFACE CONVERTER.

There is also a need for an economical design and implementation ofGigabit Ethernet using the relatively inexpensive and readily availableoff-the-shelf hardware, such as GIGABIT INTERFACE CONVERTERs, andsoftware in conjunction with WDM technology to minimize the number ofoptical fiber needed to achieve 1000Base-T connectivity for Local AreaNetworks (LANs), Campus Area Networks (CAN), Metro Area Networks (MANs),Wide Area Networks (WANs), and the like.

Therefore, it is an object of the present invention is to provide amethod and apparatus for economical Gigabit Ethernet point-to-point,full-duplex and bi-directional connectivity using one optical fiber.

A first aspect of the present invention is a method created forbi-directional full duplex Gigabit Ethernet connectivity in a local areanetwork using a single optical fiber for data communication, including:converting an electrical signal to be communicated in a first directioninto an optical signal of a first wavelength to be communicated in thefirst direction using a standard Gigabit Interface Converter devicehaving an optical output and an optical input operating at a firstwavelength; converting the optical signal to an optical signal of asecond wavelength to be communicated in the first direction; couplingthe optical signal of a second wavelength on the single optical fiberfor communicating in the first direction.

A second aspect of the invention is a system for Gigabit Ethernetconnectivity including: a first node, including: one Gigabit InterfaceConverter having an optical output port and an optical input portoperating at a first wavelength; a wavelength converter having anoptical input port and an optical output port, wherein the input port ofwavelength converter receives the optical signal of the firstwavelength, and the output port of said wavelength converter provides aconverted signal of a second wavelength; and a wave divisionmultiplexer/demultiplexer coupled to the output port of the wavelengthconverter and to the optical input of the one Gigabit InterfaceConverter of the first node.

The second aspect of the invention further includes: a second node,including: one Gigabit Interface Converter an optical output port and anoptical input port operating at a first wavelength; a wavelengthconverter having an optical input port and an optical output port,wherein the input port of wavelength converter receives the opticalsignal of the second wavelength, and the output port of the wavelengthconverter provides a converted signal of the first wavelength; a wavedivision multiplexer/demultiplexer coupled to the input port of thewavelength converter and to the optical output of the one GigabitInterface Converter of the second node; and a single optical fibercoupled to the wave division multiplexer/demultiplexer of the first nodeand of the second node, wherein the single optical fiber provides abi-direction transmission of optical signals between the first andsecond node.

Further aspects of the present invention will become readily apparent tothose skilled in the art from the following detailed description,wherein a preferred embodiment of the invention is shown and described,simply by way of illustration. As will be realized, the presentinvention incorporates other and different embodiments, and can bemodified in various respects without departing from the invention.Accordingly, the drawings and description are to be regarded asillustrative nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

Reference is made to the attached drawing, wherein elements having thesame reference numeral designations represent like elements throughout,and wherein:

FIG. 1 is a schematic illustration of a conventional point-to-pointGigabit Ethernet between Node A and Node B using two optical fibers;

FIG. 2A is an exemplary perspective illustration of a GIGABIT INTERFACECONVERTER;

FIG. 2B is a top view of the GIGABIT INTERFACE CONVERTER of FIG. 2A;

FIG. 2C is a back-end view of the GIGABIT INTERFACE CONVERTER FIG. 2A;

FIG. 2D is a side view of the GIGABIT INTERFACE CONVERTER of FIG. 2A;

FIG. 3A is a schematic illustration point-to-point Gigabit Ethernetbetween Node A′ and Node B′ using single optical fiber in accordancewith a preferred embodiment of the present invention;

FIG. 3B is a schematic illustration of another embodiment using awavelength converter;

FIG. 3C is schematic illustration of a wavelength converter;

FIG. 4 is a schematic illustration of another embodiment of a GIGABITINTERFACE CONVERTER Ethernet system using WDM and a single optical fiberof the present invention;

FIG. 5 is a schematic illustration of another embodiment of a GIGABITINTERFACE CONVERTER Ethernet system using WDM and a single optical fiberof the present invention;

FIG. 6A is a schematic illustration of a conventional GIGABIT INTERFACECONVERTER with a transmitter and a receiver operating at a samewavelength;

FIG. 6B is a schematic illustration of a GIGABIT INTERFACE CONVERTER ofthe preferred embodiment with a transmitter and a receiver operating atdifferent wavelengths.

DETAILED DESCRIPTION

The preferred embodiment uses a novel combination of GIGABIT INTERFACECONVERTERS and wave division multiplexer/demultiplexers coupled to asingle optical fiber to provide full-duplex bi-directional transmissionof optical signals in an Ethernet environment. As illustrated in FIG. 1and described above, a conventional GIGABIT INTERFACE CONVERTER Ethernetsystem 1 commonly used today is shown with Node A comprising a GIGABITINTERFACE CONVERTER transceiver 2 and Node B comprising a GIGABITINTERFACE CONVERTER transceiver 3. Communication between Node A and NodeB are accomplished via two optical fibers 4 and 5. In this conventionalGIGABIT INTERFACE CONVERTER Ethernet system, GIGABIT INTERFACE CONVERTERtransceiver 2 transmits, using a single-mode laser or a multi-mode LED,a light signal of a selected wavelength, and receives a transmittedlight signal using an optical detector operated that the samewavelength.

As noted above, the conventional GIGABIT INTERFACE CONVERTER Ethernetsystem requires Node A to transmit a signal to Node B on optical fiber 5and to receive transmitted signal from Node B on optical fiber 4. Hence,bi-directional full-duplex signal transmission requires two opticalfibers regardless of the number of channels.

An off-the-shelf GIGABIT INTERFACE CONVERTER is illustrated in FIGS. 2Athrough 2D. Examples of GIGABIT INTERFACE CONVERTER transceivers havingthe form factor shown in FIGS. 2A through 2D are Finisar's shortwaveFTR-8519-3 and FTR-8519-3-2.5, long-wave FTR-1319-3A and FTR-1319-5A30,and extended FTR-1519. At the time of this wilting, the GIGABITINTERFACE CONVERTER transceiver FTR-1319 is priced at about $449.00,FTR-1519 at about $1826.00, FTR-8519-3 at about $115.00, andFTR-8519-3-2.5 at about $288.00, if purchased in single quantity.

Generally, each GIGABIT INTERFACE CONVERTER transceiver having atransmitting channel and a receiving channel is considered as a2-channel transceiver. The specification details of Finisar's GIGABITINTERFACE CONVERTER are well known, as they are published and madeavailable through Finisar. The FTR-8519-3 is a device having a shortwavelaser operating at 850 nm multi-mode. The FTR-1319-5A-30 has a longwavelaser of 1310 nrn single-mode. The FTR-1519 has a longwave laser of 1550nm single-mode.

As illustrated in FIG. 2A, GIGABIT INTERFACE CONVERTER 21 includes asingle-mode long-wave laser transmitter that provides an optical signaloutput at transmit port 22. The optical signal output has a wavelengthof 850 nm in the preferred embodiment. Also, a receiver includes anoptical detector that detects optical signals having a wavelength of 850nm at receiving port 23. Also shown in FIG. 2A are protecting caps 24,which are provided for the transmit port 24 and receiving port 23.

As discussed above, in a conventional GIGABIT INTERFACE CONVERTEREthernet system, in order to utilize a common GIGABIT INTERFACECONVERTER transceiver such as the FTR-8519-3-2.5, in an Ethernetnetwork, two optical fibers are needed to separate the signaltransmitted from port 22 and the signal received by receiving port 23.With a conventional GIGABIT INTERFACE CONVERTER, it is not possible tosimultaneously transmit two signals of the same wavelength over a singleoptical fiber without creating signal interference from the signals ofthe same wavelength traveling in opposite directions.

Applicant has found that off-the-shelf GIGABIT INTERFACE CONVERTERtransceivers can be modified in unconventional ways to realize GigabitEthernet connectivity using only one optical fiber for full-duplexbidirectional transmission of optical signals between two nodes in apoint-to-point network.

A conventional GIGABIT INTERFACE CONVERTER and Applicant's modifiedGIGABIT INTERFACE CONVERTER a are shown in FIGS. 6A and 6B,respectively. In FIG. 6A, a conventional GIGABIT INTERFACE CONVERTERtransceiver 61 with a single wavelength, i.e. the transmitter and thereceiver both operate at the same wavelength λ₃ is illustratively shown.In FIG. 6B, a modified GIGABIT INTERFACE CONVERTER transceiver 62 of thepresent invention with dual-wavelength capability, i.e. the transmitteroperates at a wavelength λ₃ and the receiver operates at a differentwavelength λ₄, is illustratively shown. To modify the GIGABIT INTERFACECONVERTER of FIG. 6B, either the transmitter or the receiver is simplyreplaced with a different unit that operates at a different wavelength.Such a replacement or modification has no affects on the originalfunctions of the GIGABIT INTERFACE CONVERTER. A fully functional systemhas been successfully implemented and is described below with respect toFIG. 3A.

421 Turning now to FIG. 3A, in a preferred embodiment of the presentinvention, at least a pair of conventional GIGABIT INTERFACE CONVERTERtransceivers is modified to have a transmitter and a receiver operatingat different wavelengths from each other. As illustrated in FIG. 3A, aGigabit Ethernet connectivity system 31 is achieved using a pair ofGIGABIT INTERFACE CONVERTER transceivers 32 and 33, wave divisionmultiplexer and demultiplexer pair 34 and 35, and a single multi-modeoptical fiber 36. Of course, for the sake of simplicity, details of theGigabit Ethernet connectivity system 31 are omitted except for the keycomponents illustrated schematically in FIG. 3A. For example, GIGABITINTERFACE CONVERTER transceivers 32 and 33 are electronically andphysically coupled to a host computer or to a chassis housing multipleGIGABIT INTERFACE CONVERTERs in a known manner.

In FIG. 3A, a first GIGABIT INTERFACE CONVERTER transceiver 32 at NodeA′ includes a transmitter having a laser generating optical signals of afirst wavelength λ₁, and a receiver having an optical detector fordetecting transmitted optical signals of a second wavelength λ₂. Asecond GIGABIT INTERFACE CONVERTER transceiver at Node B′ includes atransmitter having a laser generating optical signals of the secondwavelength λ₂, and a receiver having an optical detector for detectingtransmitted optical signals of the first wavelength λ₁. Connected to thefirst GIGABIT INTERFACE CONVERTER transceiver 32 is a first wavedivision multiplexer and demultiplexer 34, and connected to the secondGIGABIT INTERFACE CONVERTER transceiver is a second wave divisionmultiplexer and demultiplexer 35. Such multiplexers and demultiplexersare well known to complete a connection between Node A′ and Node B′, amulti-mode optical fiber 36 is utilized to carry signals of the firstwavelength λ₁ and of the second wavelength λ₂ respectively traveling inopposite directions simultaneously.

In order to have the transmitter and receiver of a standard GIGABITINTERFACE CONVERTER operating at different wavelengths from each other,it is desirable, for example, to physically replace the transmitter ofthe first GIGABIT INTERFACE CONVERTER 32 with another type oftransmitter having a laser generating optical signals of wavelength λ₁while keeping the receiver having an optical detector detecting opticalsignals of wavelength λ₂. Of course, the second GIGABIT INTERFACECONVERTER 33 is a complement of the first GIGABIT INTERFACE CONVERTER32. That is, the receiver of GIGABIT INTERFACE CONVERTER 33 is replacedwith a different type that is capable of detecting optical signalshaving a wavelength of λ₁.

The system illustrated in FIG. 3A can be implemented using, for example,a Finisar FTR-8519 GIGABIT INTERFACE CONVERTER transceiver and a FinisarFTR-1319 GIGABIT INTERFACE CONVERTER transceiver and swapping theirtransmitter or receiver. The FTR-8519 has a receiver and transmitteroperating at 850 nm wavelength, and the FTR-1319 has a receiver and atransmitter operating at 1310 nm wavelength. After a swap, the modifiedFTR-1319 may have the FTR-8519's 850 nm transmitter, and the FTR-8519may have the FTR-1319's 1310 nm transmitter.

By simply replacing the transmitter or the receiver, an inexpensiveGIGABIT INTERFACE CONVERTER transceiver can operate at dual wavelengthsas shown. The functionality of a GIGABIT INTERFACE CONVERTER transceiverof the preferred embodiment having dual wavelength characteristic is nodifferent than that of the conventional GIGABIT INTERFACE CONVERTERhaving a single wavelength characteristic. In other words, no firmwareor software modification is necessary to operate the GIGABIT INTERFACECONVERTERs 32 and 33 in the exemplary system of FIG. 3A.

In the system of FIG. 3A. the wave division multiplexers/demultiplexers(WDM) 34 and 35 can also be off-the-shelf components. The optical fiberconnecting the multiplexer/demultiplexer 34 and 35 can be a multi-modefiber.

Of course, the number of channels in a Gigabit Ethernet connectivityusing GIGABIT INTERFACE CONVERTER transceivers, wave divisionmultiplexer/demultiplexers and a single fiber optic of the presentinvention is not necessarily limited to a 2-channel system asillustrated in FIG. 3A. Alternatively, a 4-channel system is shown inFIG. 4. The number of channels can be expanded even further whileutilizing only one optical fiber to carry data that are simultaneouslyand bi-directionally transmitted. Naturally, each channel in such asystem should operate at a wavelength that is different from theremaining channels in order to take advantage of the wavelength divisionmultiplexing and demultiplexing technique.

In FIG. 4, GIGABIT INTERFACE CONVERTER transceivers 44 and 45 and wavedivision multiplexer/demultiplexer 43 constitute Node C. Further,GIGABIT INTERFACE CONVERTER transceivers 46 and 47 and wave divisionmultiplexer/demultiplexer 42 constitute Node D. Node C and Node D arelinked by a single optical fiber 41.

At Node C, GIGABIT INTERFACE CONVERTER transceiver 44 may havetransmitter having a 1470 nm laser output and a receiver having anoptical detector for a 1510 nm optical signal, and GIGABIT INTERFACECONVERTER transceiver 45 may have a transmitter having a 1550 nm laseroutput and a receiver having an optical detector for 1610 nm opticalsignal. Other types of transmitters and receivers can be utilized.

At Node D, GIGABIT INTERFACE CONVERTER transceiver 46 may havetransmitter having a 1510 nm laser output and a receiver having anoptical detector for 1470 nm optical signal, and GIGABIT INTERFACECONVERTER transceiver 47 may have transmitter having a 1610 nm laseroutput and a receiver having an optical detector for a 1550 nm opticalsignal. The wavelength of each channel shown in FIG. 4 is forillustrative purposes. Other wavelengths may be used, as GIGABITINTERFACE CONVERTER transceivers are manufactured with a wide range ofsingle-mode lasers operating at a variety of wavelengths, as notedabove. Similar to the embodiment shown in FIG. 3A, the GIGABIT INTERFACECONVERTER transceivers 44, 45, 46, and 47 are dual-wavelength GIGABITINTERFACE CONVERTER transceivers. That is each GIGABIT INTERFACECONVERTER transceiver has a transmitter and a receiver that operate at adifferent wavelength.

In another embodiment, as shown in FIGS. 3B and 3C, instead of swappingthe transmitter to achieve a dual-wavelength capability as shown in FIG.3A, a wavelength converter 70 is utilized to convert a optical signal ofa first wavelength λ₁ which is to be transmitted in a first direction ,to a second wavelength λ₂ to be transmitted in the first direction.

FIG. 3B shows a GIGABIT INTERFACE CONVERTER 71 having a receiver andtransmitter operating at a first wavelength λ₁. An optical signal fromGIGABIT INTERFACE CONVERTER 71 at Node A″ is transmitted to thewavelength converter 70 where the optical signal is converted into asecond wavelength λ₂. The optical signal of the second wavelength λ₂ isthen multiplexed via the WDM 34 and transmitted via the single opticalfiber 36 to Node B″.

FIG. 3C is a simplified but detailed drawing of a wavelength converter70 showing only the key features to illustrate its function.Essentially, the wavelength converter includes two off-the-shelf GIGABITINTERFACE CONVERTERS 73 and 74 electrically coupled to each other. Thefirst wavelength λ₁ from GIGABIT INTERFACE CONVERTER 71 is received bythe receiver of GIGABIT INTERFACE CONVERTER 73. The optical signal isconverted to an interim electrical signal that is electrically coupledto GIGABIT INTERFACE CONVERTER 74, which converts the interim electricalsignal to an optical of the second wavelength λ₂ that is to betransmitted from Node A″ in the first direction.

A similar arrangement is easily implemented to convert the opticalsignal of the second wavelength to an optical signal of the first wavelength A at Node B″. Using the same technique illustrated in FIG. 3C. anoptical signal of a wavelength may be converted to any desirablewavelength.

In another embodiment, not illustrated, GIGABIT INTERFACE CONVERTERtransceivers utilize an optical filter as a band-pass filter to select aspecific desirable operating optical wavelength may be modified byswapping the optical filter of the receiver so that the optical filterof the receiver has a different operating wavelength than an opticalfilter in the transmitter. The swapping of the filter also provides theeffect of dual-wavelength capability illustrated in FIG. 6B. Opticalfilters are found in inexpensive, short-haul GIGABIT INTERFACE CONVERTERtransceivers that utilize LED as a light source in their transmitter.

In yet another embodiment, as shown in FIG. 5, the effect of producingdual-wavelength transceivers is achieved by using three off-the-shelfGIGABIT INTERFACE CONVERTER transceivers to make a wavelength converter.

In FIG. 5, an illustration of a single Node E is shown with a singleoptical fiber long-haul connectivity to Node F. At node E, aninexpensive multi-mode GIGABIT INTERFACE CONVERTER transceiver 51 withshort-haul capability is electrically coupled to a host computer, notshown, in a known manner. The multi-mode GIGABIT INTERFACE CONVERTERtransceiver 51 can have a LED-type transmitter and a receiver having anoptical detector. Both the receiver and transmitter of multi-modeGIGABIT INTERFACE CONVERTER transceiver 51 operate at a predeterminedwavelength λ₅. Long-haul connectivity typically requires a GIGABITINTERFACE CONVERTER with a longwave single-mode laser, and short-haulconnectivity typically requires shortwave laser or multi-mode laser.

Optically coupled to the multi-mode GIGABIT INTERFACE CONVERTERtransceiver 51 is a wave-length converter 50, as shown in the dotted boxin FIG. 5, which comprises three GIGABIT INTERFACE CONVERTERtransceivers 52, 53, and 54. The GIGABIT INTERFACE CONVERTER transceiver52 is an inexpensive short-haul multi-mode GIGABIT INTERFACE CONVERTERand can be an optically coupled to the GIGABIT INTERFACE CONVERTERtransceiver 51. In order to provide long-haul full-duplex single opticalfiber connectivity to at least one other node using wave divisionmultiplexing/demultiplex technique, GIGABIT INTERFACE CONVERTERtransceivers 53 and 54, which can be long wave single mode transceivers,are preferably coupled to the short-haul multi-mode GIGABIT INTERFACECONVERTER 52 electrically.

In the system of FIG. 5, optical signals transmitted from Node E to NodeF are transmitted via the transmitter of the multi-mode GIGABITINTERFACE CONVERTER transceiver 51, through the multi-mode GIGABITINTERFACE CONVERTER transceiver 52 and the single-mode GIGABIT INTERFACECONVERTER transceiver 54, at wavelength λ₆, and a wave divisionmultiplex/demultiplexer 55. Optical signals are transmitted from Node Eto Node F via the wave division multiplexer/demultiplexer 55, a receiverof the single-mode GIGABIT INTERFACE CONVERTER transceiver 53, operatingat wavelength λ₇, through the multi-mode GIGABIT INTERFACE CONVERTERtransceiver 52, and ultimately to the multi-mode GIGABIT INTERFACECONVERTER transceiver 51.

611 The embodiment of the present invention illustrated in FIG. 5 doesnot require any swapping of a receiver component or a transmittercomponent as in the embodiment shown in FIG. 3A and FIG. 4 becauseconverter 50 is used to convert the wavelengths. Further, a mix ofinexpensive short-haul multi-mode GIGABIT INTERFACE CONVERTERtransceivers and the more expensive long-haul single-mode GIGABITINTERFACE CONVERTER transceiver can be implemented as discussed above toprovide an economical full-duplex and bi-directional wave divisionmultiplex communication over single optical fiber to each node. Also, asdescribed above, single fiber communication can be accomplished toplural nodes. Of course, the distances between nodes are determined bythe type of transmitter laser and the optical fiber used.

The present invention is a novel and simple application of GIGABITINTERFACE CONVERTER transceivers permits to achieve full-duplex andbidirectional Gigabit Ethernet connectivity over one fiber. Theinvention can use standard “off the shelf” modules modified to operateat different wavelengths. The invention can be applied to applycommunication between any devices. Further, the invention can beconfigured in various manners to achieve the desired communication. Thewavelength conversion can be accomplished in any manner.

In the preferred embodiments, coupling/decoupling is accomplished bymultiplexers/de-multiplexers. However, this function can be accomplishedin any manner. Also, in the preferred embodiments, light forcommunication in one direction is changed in frequency. However, anyattribute of the light can be changed so that light in one direction canbe distinguished from light in another direction. For example amplitudeor polarization can be changed.

It will be apparent that many modifications and variations may beeffected without departing from the scope of the novel concepts of thepresent invention as defined by the appended claims and legalequivalents.

1. (canceled)
 2. A method for bi-directional data connectivity over asingle optical fiber, comprising: receiving, at a first GigabitInterface Converter, a first signal to be communicated in a firstdirection; converting, using the first Gigabit Interface Converter, thefirst signal from an optical signal of a first wavelength to anelectrical signal; communicating the first signal as the electricalsignal from the first Gigabit Interface Converter to a second GigabitInterface Converter; converting, using the second Gigabit InterfaceConverter, the first signal from the electrical signal to an opticalsignal of a second wavelength, the second wavelength being differentfrom the first wavelength; and coupling the first signal of the secondwavelength to an optical fiber to transmit the first signal in the firstdirection.
 3. The method according to claim 2, wherein the first signalof the second wavelength is coupled to the optical fiber via awave-division multiplexing/demultiplexing device.
 4. The methodaccording to claim 3, further comprising: receiving from the opticalfiber, at the wave-division multiplexing/demultiplexing device, a secondsignal to be communicated in a second direction; communicating thesecond signal from the wave-division multiplexing/demultiplexing deviceto the second Gigabit Interface Converter; converting, using the secondGigabit Interface Converter, the second signal from a second opticalsignal of the second wavelength to a second electrical signal;communicating the second signal as the second electrical signal from thesecond Gigabit Interface Converter to a first Gigabit InterfaceConverter; and converting, using the first Gigabit Interface Converter,the second signal from the second electrical signal to a second opticalsignal of the first wavelength.
 5. The method according to claim 4,wherein the first signal and the second signal are transmittedsimultaneously on the optical fiber.
 6. The method according to claim 3,further comprising: receiving from the optical fiber, at thewave-division multiplexing/demultiplexing device, a second signal to becommunicated in a second direction; communicating the second signal fromthe wave-division multiplexing/demultiplexing device to a third GigabitInterface Converter; converting the second signal from an optical signalof a third wavelength to a second electrical signal, the thirdwavelength being different from the first wavelength and the secondwavelength; communicating the second signal as the second electricalsignal from the third Gigabit Interface Converter to the first GigabitInterface Converter; converting the second signal from the secondelectrical signal to an optical signal of the first wavelength; andcommunicating the second signal of the first wavelength from the firstGigabit Interface Converter in the second direction.
 7. The methodaccording to claim 6, wherein the first signal and the second signal aretransmitted simultaneously on the optical fiber.
 8. A wavelengthconverter, comprising: a first Gigabit Interface Converter including afirst optical transmitter, a first optical receiver, a first electricalinput and a first electrical output, the first optical transmitter andthe first optical receiver operating at a first wavelength; and a secondGigabit Interface Converter including a second optical transmitter, asecond optical receiver, a second electrical input and a secondelectrical output, the second optical transmitter and the second opticalreceiver operating at a second wavelength, the first wavelength beingdifferent from the second wavelength, the first electrical output beingcoupled to the second electrical input.
 9. The wavelength converteraccording to claim 8, wherein the second electrical output is coupled tothe first electrical input.
 10. The wavelength converter according toclaim 8, further comprising: a third Gigabit Interface Converterincluding a third optical transmitter, a third optical receiver, a thirdelectrical input and a third electrical output, the third opticaltransmitter and the third optical receiver operating at a thirdwavelength, the third wavelength being different from the firstwavelength and the second wavelength, wherein the third electricaloutput is coupled to the first electrical input.
 11. A system forbi-directional data connectivity over a single optical fiber,comprising: a first Gigabit Interface Converter including a firstoptical transmitter operating at a first wavelength and a first opticalreceiver operating at a second wavelength; a first wavelength-divisionmultiplexing/demultiplexing device coupled to the first GigabitInterface Converter so as to be operable to receive a first opticalsignal of the first wavelength from the first optical transmitter and totransmit a second optical signal of the second wavelength to the firstoptical receiver; and an optical fiber coupled to the firstwavelength-division multiplexing/demultiplexing device.
 12. The systemaccording to claim 11, further comprising: a second Gigabit InterfaceConverter including a second optical transmitter operating at the secondwavelength and a second optical receiver operating at the firstwavelength; and a second wavelength-division multiplexing/demultiplexingdevice coupled to the optical fiber, the second wavelength-divisionmultiplexing/demultiplexing device being further coupled to the secondGigabit Interface Converter so as to be operable to receive the secondoptical signal of the second wavelength from the second opticaltransmitter and to transmit the first optical signal of the firstwavelength to the second optical receiver.
 13. The system according toclaim 11, further comprising a second Gigabit Interface Converterincluding a second optical transmitter operating at a third wavelengthand a second optical receiver operating at the fourth wavelength, thefirst wavelength-division multiplexing/demultiplexing device beingcoupled to the second Gigabit Interface Converter so as to be operableto receive a third optical signal of the third wavelength from thesecond optical transmitter and to transmit a fourth optical signal ofthe fourth wavelength to the second optical receiver.
 14. The systemaccording to claim 13, further comprising: a third Gigabit InterfaceConverter including a third optical transmitter operating at the secondwavelength and a third optical receiver operating at the firstwavelength; a fourth Gigabit Interface Converter including a fourthoptical transmitter operating at the fourth wavelength and a fourthoptical receiver operating at the third wavelength; and a secondwavelength-division multiplexing/demultiplexing device coupled to theoptical fiber, the second wavelength-divisionmultiplexing/demultiplexing device being coupled to the third GigabitInterface Converter so as to be operable to receive the second opticalsignal of the second wavelength from the third optical transmitter andto transmit the first optical signal of the first wavelength to thethird optical receiver, the second wavelength-divisionmultiplexing/demultiplexing device being coupled to the fourth GigabitInterface Converter so as to be operable to receive the fourth opticalsignal of the fourth wavelength from the fourth optical transmitter andto transmit the third optical signal of the third wavelength to thefourth optical receiver.
 15. A Gigabit Interface Converter, comprising:a signal processing circuit configured to convert a first electricalsignal to a first optical signal and configured to convert a secondoptical signal to a second electrical signal; at least one electricalinput coupled to the signal processing circuit and configured to receivethe first electrical signal; at least one electrical output coupled tothe signal processing circuit and configured to transmit the secondelectrical signal; an optical signal output coupled to the signalprocessing circuit and configured to transmit the first optical at afirst wavelength; and an optical detector coupled to the signalprocessing circuit and configured to detect the second optical signal ata second wavelength, the second wavelength being different from thefirst wavelength.